When the remnants of Hurricane Ida pummeled New York City with more than 3 inches of rain in just one hour, the city struggled to soak it up. Instead, streets and subways flooded as storm drains were overwhelmed, basement apartments were inundated, and more than a dozen people died.

That September 2021 storm and the ones before it, including a cloudburst downpour during Tropical Storm Elsa in July, have forced New York to take a hard look at becoming a “spongier” city — one that combines nature-based green infrastructure like street-side rain gardens with gray infrastructure like storm drains to divert or absorb water and prevent catastrophic flooding.

“New York City is preparing for both chronic storm events — these cloudburst events that we see occurring more and more frequently — as well as extreme storm events like Ida,” says Jennifer Cherrier, a professor of earth and environmental sciences at Brooklyn College. On top of that, the city also faces mounting risks from storm surges, like during Hurricane Sandy in 2012.